Convert old "into" code to the collectors

[Brian Goetz]

The into() method, and the concept behind it, is gone.  And good riddance to it!  It was bad in so many ways.  

It is possible we may add some convenience methods like toList(), which would be shorthand for .collect(Collectors.toList()).  

On Jan 16, 2013, at 8:25 AM, Marcos Antonio wrote:

> 
> So the bottom line is that I cannot use an existing collection anymore as I used to do with the "into" method, right?
> Are there any alternatives?
> 
> For the time being, this is my workaround:
> 
> propriedadesChavePai.addAll(
>    chave.getPropriedadesChavePai().stream().
>        map(PropriedadeChavePai::new).
>        collect(Collectors.<PropriedadeChavePai>toList())
> );
> 
> Very bulky.
> 
> Marcos
> 
> ----------------------------------------
>> Date: Wed, 16 Jan 2013 15:58:29 +0000
>> From: maurizio.cimadamore at oracle.com
>> To: marcos_antonio_ps at hotmail.com
>> CC: lambda-dev at openjdk.java.net
>> Subject: Re: Convert old "into" code to the collectors
>> 
>> 
>> I think the toCollection method is designed to convert a constructor
>> reference (passed as a Supplier) into a new Collector, which is used to
>> carry out the 'collect' operation. In other words, I don't think you can
>> pass a plain collection to 'toCollection'.
>> 
>> Maurizio
>> 
>> 
>> On 16/01/13 15:41, Marcos Antonio wrote:
>>> Here are the compiler error messages for the two case:
>>> 
>>> List<PropriedadeChavePai> propriedadesChavePai = new ArrayList<>();
>>> 
>>> chave.getPropriedadesChavePai().stream().
>>> map(PropriedadeChavePai::new).
>>> collect(Collectors.<PropriedadeChavePai>toCollection(propriedadesChavePai));
>>> 
>>> [javac] C:\desenvolvimento\desktop\desenvolvimento\br\desenvolvimento\dados\CriadorChave.java:259: error: method toCollection in class Collectors cannot be applied to given types;
>>> [javac] collect(Collectors.<PropriedadeChavePai>toCollection(propriedadesChavePai));
>>> [javac] ^
>>> [javac] required: Supplier<C>
>>> [javac] found: List<PropriedadeChavePai>
>>> [javac] reason: actual and formal argument lists differ in length
>>> [javac] where C,T are type-variables:
>>> [javac] C extends Collection<T> declared in method <T,C>toCollection(Supplier<C>)
>>> [javac] T extends Object declared in method <T,C>toCollection(Supplier<C>)
>>> [javac] 1 error
>>> 
>>> --------------------------------------------------------------------------
>>> 
>>> List<PropriedadeChavePai> propriedadesChavePai = new ArrayList<>();
>>> 
>>> chave.getPropriedadesChavePai().stream().
>>> map(PropriedadeChavePai::new).
>>> collect(Collectors.<PropriedadeChavePai>toList(propriedadesChavePai));
>>> 
>>> [javac] C:\desenvolvimento\desktop\desenvolvimento\br\desenvolvimento\dados\CriadorChave.java:259: error: method toList in class Collectors cannot be applied to given types;
>>> [javac] collect(Collectors.<PropriedadeChavePai>toList(propriedadesChavePai));
>>> [javac] ^
>>> [javac] required: no arguments
>>> [javac] found: List<PropriedadeChavePai>
>>> [javac] reason: actual and formal argument lists differ in length
>>> [javac] 1 error
>>> 
>>> Marcos
>>> 
>>> ----------------------------------------
>>>> Date: Wed, 16 Jan 2013 15:05:22 +0000
>>>> From: maurizio.cimadamore at oracle.com
>>>> To: marcos_antonio_ps at hotmail.com
>>>> CC: lambda-dev at openjdk.java.net
>>>> Subject: Re: Convert old "into" code to the collectors
>>>> 
>>>> On 16/01/13 14:34, Marcos Antonio wrote:
>>>>> Hello, everybody!
>>>>> 
>>>>> Before build b73 I had code like this:
>>>>> 
>>>>> List<PropriedadeChavePai> propriedades = new ArrayList<>();
>>>>> 
>>>>> chave.getPropriedadesChavePai().stream().
>>>>> map(PropriedadeChavePai::new).
>>>>> into(propriedades);
>>>>> 
>>>>> Now I'm having trouble trying to convert it to use the new Collectors. I have tried something like this:
>>>>> 
>>>>> chave.getPropriedadesChavePai().stream().
>>>>> map(PropriedadeChavePai::new).
>>>>> collect(Collectors.toCollection(propriedades));
>>>>> 
>>>>> but it didn't work and I couldn't figure out the right thing to do.
>>>>> 
>>>>> Thank you in advance.
>>>>> 
>>>>> Marcos
>>>>> 
>>>> What do you mean it didn't work? Did you get an error message from the
>>>> compiler? If so, can you please paste it?
>>>> 
>>>> Maurizio
>> 		 	   		  
>